Eagle Mountain, UT Building Setbacks & Zoning: Lot Coverage Limits (2026)
Key Facts
- Applies to
- Average lot slope between 8% and 25%
- Best case
- 30% impervious, slope <=25%, slightly erodible soil
- Mid case
- 20% impervious on moderately erodible soil
- Worst case
- 5% impervious, slope <=15%, moderately erodible
- Hard cap
- 1% impervious; no development above 25% slope
Summary
On lots with average natural slope between 8 and 25 percent, Eagle Mountain limits impervious coverage on a sliding scale by slope and soil erodibility: up to 30 percent on gentle, stable ground down to as little as 5 percent on steeper, more erodible ground, with development barred outright above 25 percent slope, under EMMC 16.40.090.
Property that has an average slope between eight and 25 percent shall comply with Diagram 16.40.090 and the following standards: A. Thirty Percent Impervious Lot Cover. A lot may be developed with 30 percent of the total lot area covered with impervious area if the average slope of the ground is 25 percent or less and the soils are only slightly erodible. ... ... C. Twenty Percent Impervious Lot Cover. A lot may be developed with 20 percent of the total lot area covered with impervious area under the following conditions: (1) if the average slope of the ground is 25 percent or less and the soils are moderately erodible; (2) if the average slope of the ground is 15 percent or less and the soils are erodible. ... ... E. One Percent Impervious Lot Cover. Development is prohibited on slopes greater than 25 percent.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance O-34-2026, passed August 4, 2026).
Full Breakdown
090 illustrates the same limits by slope and soil class. A lot with a slope of 25 percent or less on only slightly erodible soil may cover 30 percent of its area with impervious surface; on slightly-to-moderately erodible soil at the same slope the cap drops to 25 percent; on moderately erodible soil at 25 percent slope, or on erodible soil at 15 percent slope or less, it drops to 20 percent; on moderately erodible soil at 15 percent slope or less it falls to just 5 percent.
The code works the math for a 1,500-square-foot house with another 1,500 square feet of driveway, sidewalk and patio: that combination needs a 10,000-square-foot lot at the 30 percent tier but a 60,000-square-foot lot at the 5 percent tier. Above 25 percent average slope, development is prohibited outright and the effective impervious allowance is one percent. Section F explains why: steeper ground speeds up runoff and cuts infiltration, and sandy or silty soils erode easily because they lack clay to bind particles together, while clay-rich soils resist washing away. 040(E) before the city engineer will approve clearing, excavation or grading.
Violations & Fines
A development plan that exceeds the impervious cap for its lot's slope and soil class fails plan review under the runoff and erosion control plan required by EMMC 16.40.040 and will not receive city engineer approval to clear, excavate or grade under EMMC 16.40.030. On any portion of a lot where the natural slope equals or exceeds 25 percent, EMMC 16.40.070 separately bars excavation, grading or fill outright, regardless of the impervious percentage proposed.
Frequently Asked Questions
What if my lot's average slope is under 8 percent?
Can I build at all on a slope over 25 percent?
How much does soil type change my impervious limit?
What does the city require before I can start grading a sloped lot?
Sources & Official References
Other rules in Eagle Mountain
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Lot Coverage Limits in Nearby Cities
How other cities in Utah County handle lot coverage limits.